前置編碼正交分頻多工系統：效能與頻率偏移敏感度之分析

Abstract

在這篇論文裡，我們將探討在具有前置器的正交分頻多工(OFDM)系統。加了前置器後，在接收器的末端加上反向前置器使整個系統保持和傳統的OFDM系統一樣的沒有符號間干擾(ISI)。我們會對具有數位傅立葉轉換(DFT)、哈達瑪(Hadamard)和數位餘弦轉換(DCT)前置器的OFDM系統的誤碼率進行研究。當前置器是一個單位矩陣的時候，這個系統就會變成是傳統的正交分頻多工系統；當前置器是一個數位傅立葉轉換矩陣時，系統就會變成是具有循環複製的單頻(SC-CP)系統。我們也將會討論到正交分頻多工系統和具有循環複製的單頻系統對頻率偏移的敏感度。

In this thesis, we consider OFDM system with an orthogonal precoder T. The inverse of the precoder is cascaded to the end of the receiver and the overall system is ISI free as the conventional OFDM system. We investigate the bit error rate (BER) performance of the OFDM system with DFT, Hadamard and DCT precoders. When the precoder is the the identity matrix, the system is the conventional OFDM system. When the precoder is the DFT matrix, the system become the SC-CP (single-carrier with cyclic prefix system). We will consider the sensitivity of precoded OFDM system to carrier frequency offset. In particular, the sensitivity of the conventional OFDM and SC-CP system will be analyzed.